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topic 4532

Waste Water Treatment.


Once in a while we have to change our cyanide stripping bath ( 25 gallons, pH 12). The cyanide concentration in this bath is 31,000 mg/L or ppm.

I would like to try the bleach / ORP meter technique for cyanide to cyanate conversion.

I am given to understand that the bleach process is not effective for high concentrations of cyanide. Would somebody know at what dilutions or ppm of cyanide would the bleach process work the best so I can dilute the bath before bleach treatment?

Ajit Menon
- Rapid City, SD, USA


This is very, very high cyanide, relative to what is usually treated by alkaline chlorination. I would dilute it by a factor of 25 - 30 with water, first. If you try to treat it straight you will get a lot or noxious, toxic cyanogen chloride gas evolution.

If this isn't practical, it would be possible to treat this type of waste electrolytically, or perhaps with hydrogen peroxide. You would need to do some bench tests to evaluate those treatments.

dave wichern
Dave Wichern
Consultant - The Bronx, New York

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